Ignition cibctoe



Jah. 14, 1936.

D. W. RANDOLPH IGNITION CIRCUIT Filed May 11, 1955 retecal im. 14, i936 antan enrsurorri IGNITION CIRCUIT Donald W. Randolph, Flint, Mich., assigner to General Motors Corporation, Detroit, Mich., a corporation oi Delaware Application May ll, i935, Serial No. 20,915

8 Claims.

This invention relates broadly to spark generating systems whose usual function it is to provide ignition for internal combustion enginesy and is an improvement over the system shown in the copending application Serial Number 668,754, filed May l, 1933 by Duffendack, Randolph and Wolfe.

The former application discloses several systems in which the current source is a low voltage one such as a car battery which acts to charge a condenser through the medium of the energy stored in the magnetic field of an inductancev breaks down and allows the condenser to dis-v charge, there will be a sudden rush of current from the condenser of short duration so that this may betermed an impulse spark system. This sudden now through the primary will of course effect a similar flow in the secondary work circuit and this ilow will cause a spark to jump at the spark plug points to ignite the fuel.

There is also disclosed in 688,754 the use oi a three element tube which acts as the valve be tween the condenser and the transformer primary to keep the current from flowing in this circuit until the condenser has received the proper charge. The electron flow, and therefore the point atfwhich the tube would allow now therethrough, is controlled by the potential of the grid and was shown with a bias furnished by a separate battery. Since the voltage necessary for this bias was found to be approximately 30 volts, this could not be supplied from the storage battery of the car but an extra battery was necessary.

It is the object of my invention to supply the necessary bias for the grid in a high frequency or impulse spark system from the circuit and original source and eliminate the need for an extra battery.

It is a further object of my invention to accomplish the above without complicating the whole system to too great an extent.

For a better understanding ci the nature and objects of this invention, reference is made to vthe following specification wherein there are described the embodiments of my invention which are illustrated in the accompanying drawing, in which, 5

The figure of the drawing is a schematic electric circuit which includes my invention.

Referring specifically to the drawing, the battery 2 has one of its terminals connected to a circuit breaker il, by Wire t, and the other of its terminals connected to one end of an inductance coil ii, by wire Bil, which wire is also connected to one terminal of a condenser i2, and one end o a primary transformer winding it. The opposite terminal of the circuit breaker connected to the battery is connected by wire it to the other end. of the inductance coil 8 and is then continued to connect with the grid it of a three element vacuum tube Zt. f lConnected in shunt across the terminals of the circuit breaker is a condenser ii by circuit t. The circuit breaker l may be operated at the correct instant by conventional connection to any desiredpart of the motor. A short distance from the connection between the wire it and the induc'tance coil t is a tap 22 on the inductance coil which separates the coil into two portions A and B. This tap is connected to th'e opposite end of the condenser i2 and also to one side of the heated element 2d of the vacuum tube by wire 2t. The relative number of turns in the coil depends upon the inductance and on the characteristics of the tube used in the system, but it was found that a total coil of 350 turns, 310 of which were used to charge the condenser, and for grid potential, was satisfactory.

A small A battery 28 is connected across the heating element 2li and serves to cause the same to heat up and glow to emit electrons. The plate il@ of the vacuum tube is connected by wire t2 d with the opposite end of the primary transformer winding. lf3. In the secondary current, the secondary 3ft of the transformer has one end connected to a common terminal which is connected to one side, that is the grounded side of the spark plug, by any metallic contact and is illustrated by the wire 36. The opposite end of the secondary winding. is connected by a. wire it through. the .central or revolving post il@ of the conventional distributer, having' a leg l2 50 which rotates in proximity with the contact points dit each of which is connected to one of the spark plugs @8 by a wire i6.

The operation of the circuit is as follows:

The battery 2 is connected in series with the Cil contact points of the circuit breaker 4 and the inductance coil 8, and when the contact points are closed, current ows from the battery to the inductance coil and the latter builds up a magnetic field therearound. When the contacts at 4 are opened the magnetic field around the inductance coil collapses and induces a ow of current in the circuit including the condenser I2, wire l0, the portion A of the inductance coil up to the tap 22, and the wire 26. This tends to charge the condenser and since the collapse of the field is comparatively slow, the charge on the condenser will gradually build up. During this time, also, the portion B of the inductance vcoil, between the connection of the 4Wire I6 and -the tap 22, is forcing current to the grid I8 which negatively biases the potential thereof to prevent electron flow between the filament and plate. As the condenser becomes charged, and flow of current from the induction coil to both the condenser and the grid lessens, the stop valve action of the tube will tend to break down due to the increase potential between the filament and the plate due to increased charge on the condenser and also the fact that the bias action of the grid has become less. When this occurs, the condenser discharges rapidly in the series circuit containing condenser I2, wire 26, lament 24, plate 30, wire 32, primary winding I4 of the transformer and wire I back of the condenser. This rapid discharge or ow in this circuit induces in the secondary work circuit a current of the same characteristics and since at this time the leg 42 of the rotating distributer is adjacent one of the points 44, this high frequency fuel.

The action of the condenser l I, in shunt across the contact points of the circuit breaker 4, is merely to cause less arc and preserve the life of the points.

It will thus be evident that I have provided a high frequency or impulse spark plug system whereby the biasing voltage for the grid is obtained by the tap on the inductance instead of requiring a necessity of a further source of voltag which will result in a similar system.

I claim:

. 1. In an ignition system, a condenser, a discharge circuit including the condenser, a three element Vacuum tube and a primary transformer coil, and means to apply a charge to the condenser said means including an induction coil, a, portion of which charges the condenser and the remainder supplies energy for the grid to bias the same and control the breakdown of the tube to allow electron flow and the condenser to discharge.

2. In a spark generating system, a condenser,

an electric valve to prevent flow until a certain potential is reached by the condenser said valve comprising a three electrode vacuum tube, and an induction coil, the major portion of which is utilized to charge the-condenser and the remainder to supply energy tobias the grid of the tube to prevent current flow until the condenser is sumciently charged.

3. In a spark generating system, a Source of current, a timed circuit breaker and an induction coil in series, a condenser connected across 10 a major portion of the induction coil, a. three element tube connected in series with the condenser which acts to preventva iiow of current therefrom until a given potential is reached and the grid of the tube connected aci-m the remainder of the induction coil to receive its potential therefrom.

4. In a high frequency generating system, a condenser, an electric valve in a discharge circuit to prevent discharge until a specific potential is acquired, biasing means within the valve and a single source of current supply for charging the condenser and supplying the biasing means.

5. In a high frequency generating system, a condenser, a discharge circuit for the condenser, a pair of spaced members that will noi'l conduct current thereacross until a specific potential has been reached in the discharge circuit, means between the members to adjust the resistance to iiow by biasing the potential and a common sourceof current for charging the condenser and supplying the biasing means.

6. In a high frequency generating system, a condenser, a discharge circuit for the' condenser, spaced members in the discharge circuit acting as a gap to prevent iiow until break-down, means between the two members to charge the characteristics ofthe gap, a single member supplying charging current to the condenser and biasing current to the means and a source of current 40 for the member.

7. In a high frequency generating system, a condenser, a discharge circuit for the condenser, spaced members in the-discharge circuit acting as a gap to prevent ow until break-down, electrical means between the two members to change the characteristics of the gap, an induction coil having taps whereby a portion of the coil charges the condenser and another portion supplies current for the biasing means and a single source of current for the coil.

8. In a high frequency generating system, a condenser, a charging circuit therefor including an induction coil, a discharge circuit including an enclosed gap and a? transformer primary, a biasing means in the gap, means for connecting the biasing means to ajportion of the inductance for its energy supply and a secondary work circuit to utilize the current through the transformer.

DONALD W. RANDOLPH. 

